Shingo Tamaru

Shingo Tamaru

Shingo Tamaru_CV

Research Description

Spin torque oscillator (STO) is a tiny magnetic layer stack which oscillates in microwave frequency range simply by injecting a DC current. However, the performance of a single STO, such as power level and frequency stability, is not good enough for practical application. Some past works observed mutual phase locking between two STOs formed close to each other. It was found that a mutually phase locked STO pair shows significantly better performance than a single STO. Therefore, it is a natural extension to try to synchronize multiple STOs for even better performance, but to the author’s knowledge, no research group has published any success of such an attempt as of 2008.

It is believed that interaction between spin waves and a STO is the underlying mutual phase locking mechanism. One STO launches spin waves as it oscillates, and the oscillation of the other STO is synchronized to the incident spin wave. However, spin wave propagation is much more complicated than usual 2D wave propagation such as membrane vibration, and so far no quantitative study has been conducted either experimentally or theoretically.

We have a Kerr imaging system for capturing spin wave propagation. The goal of this project is to study the interaction between the incident spin wave and STO by using this system in order to understand the mutual phase locking mechanism quantitatively, and eventually gain new insight for designing and characterizing multiple STO synchronization devices.